<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style type="text/css">
			*{
				margin: 0;
				padding: 0;
			}
			
			div{
				width: 200px;
				height: 300px;
				background: red;
				display: none;
			}
		</style>	
	</head>
	<body>
		<button style="background: #fff;">···</button>
		<div></div>
		<script type="text/javascript">
			var but=document.getElementsByTagName("button")[0];
			var div=document.getElementsByTagName("div")[0];
			
			but.onclick=function(){
				console.log(but.style.background);
				if(but.style.background=="rgb(255, 255, 255)"){
					div.style.display="block";
					but.style.background="#666666";
				}else{
					div.style.display="none";
					but.style.background="rgb(255, 255, 255)";
				}
			}
		</script>
	</body>
</html>
